DATABASE AND DATABASE MANAGEMENT SYSTEM Essay
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A database is an organized collection of data. The data are typically organized to model relevant aspects of reality in a way that supports processes requiring this information. For example, modeling the availability of rooms in hotels in a way that supports finding a hotel with vacancies.
DBMS stands for "Database Management System." In short, a DBMS is a database program. Technically speaking, it is a software system that uses a standard method of cataloging, retrieving, and running queries on data. The DBMS manages incoming data, organizes it, and provides ways for the data to be modified or extracted by users or other programs. Database management systems (DBMSs) are specially …show more content…
Consider the following structure:
Senior Manager 10
In this, the "child" is the same type as the "parent". The hierarchy stating EmpNo 10 is boss of 20, and 30 and
40 each report to 20 is represented by the "ReportsTo" column. In Relational database terms, the ReportsTo column is a foreign key referencing the EmpNo column. If the "child" data type were different, it would be in a different table, but there would still be a foreign key referencing the EmpNo column of the employees table.
This simple model is commonly known as the adjacency list model, and was introduced by Dr. Edgar F.
Codd after initial criticisms surfaced that the relational model could not model hierarchical data. The Windows
Registry is a hierarchical database that stores configuration settings and options on Microsoft Windows operating systems.
2. Network model
Example of a Network Model.